Ryuunosuke Natsume's parents are the brilliant inventor Kyusaku Natsume and the domineering CEO of Mishima Heavy Industries, Akiko Natsume. Kyusaku employs the resources of his wife's company and the intellect of Ryuunosuke's beloved cat to create an innovative android named Atsuko "Nuku Nuku" Natsume. Despite Kyusaku's disdain for it, Akiko desires to use her husband's technology to make lethal robots for company clients, causing Ryuunosuke to become embroiled in the explosive battles between his parents. As a typical high schooler, the android Nuku Nuku attempts to live life, portraying Ryuunosuke's older sister, yet frequently ends up acting as her family's defender. Nuku Nuku is willing to do whatever it takes to shield the people she cares about.